Need advice on getting loan

Want to buy a land lot and build a home. We own our current home and the only debt we have is our home mortgage and about £14000 in credit card debt. We want to buy the land first, and then save some money, then get the construction loan to begin building the house. Would it be better to save money for a down payment for the construction or to go ahead and pay off the credit card debt first? My concern is that the interest rates for loans right now are really good and if we pay off the credit card debt first then wait to save more for a down payment; loan rates will be a good bit higher because that will be about a 2-3 year period.